1. Field of the Invention
The present invention relates to a dry-type particle size distribution analyzer which drops a sample powder at a predetermined flow rate from a sample housing by vibrating the sample housing, supplies the dropped sample powder to a flow cell, and irradiates the sample powder with light to measure the particle size distribution.
2. Description of the Background Art
In the dry-type particle size distribution analyzer of this kind, for example, as shown in Japanese Unexamined Patent Publication No. 2003-185558, with a sample housing supported by a plate spring, absorption by an electrical magnet against the plate spring is performed without a break to thereby vibrate the sample housing whereby the sample powder is dropped and supplied to the flow cell.
In such a dry-type particle size distribution analyzer, an appropriate sample supply rate needs to be set for the measurement. The sample supply rate is reflected on the intensity of transmitted light (transmittance) and the intensity of scattered light; thus, conventionally, in order to define the sample supply rate, the operator monitors the intensity of transmitted light (transmittance) and the intensity of scattered light and adjusts the amplitude, cycle, waveform, and the like of vibration so that the values thereof reach their respective desired values.
However, these monitoring and adjustment is required not only at the initial stage but also during the measurement as needed, which involves time-consuming operation, for reasons such as that, even with same vibration, the sample supply state gradually changes depending on the amount of the sample powder remaining in the sample housing.
Further, this adjustment operation depends on the skill level of the operator. Thus, the measurement results may differ among different operators, and the adjustment operation may require some time thus leading to waste of the sample.